Apparatus for etching plates



Aug. 8, 1939. L. E. HOLLAND APPARATUS FOR ETCHING PLATES Filed Sept. 5, 1935 INVENTOR ATTORN EY 0900 mwwdtiwck Patented Aug. 8, 1939 v UNITED STATES PATENT OFFiCE APPARATUS FOR ETCHING PLATES Louis E. Holland, Kansas City, Mo.

Application September 3, 1935, Serial No. 38,926

4 Claims. (Cl. 1'77311) This invention relates to automatically conplying an etching current. The generator I is trolled electric circuits, for example circuits emactuated by a motor H2. The motors I39 and ployed in electrical etching apparatus, and has for H2 are supplied with current from service lines its principal Objects to provide a circuit of this H3 and H4 through branch wires II5I I6 and 5 character with automatic means f r s spen ing llI-l l8 connected with the terminals of the re- 5 flow of current after a predetermined time interspective motors. val; to provide for signalling suspension of the The control circuit I includes circuit closing current flow so that an operator need not be in switches I04I05I06, an ammeter IIJ'I, a volt constant watch of the apparatus; and to allow meter I08, a voltage regulator I09, an automatic 1o actuation of the signal for a predetermined time circuit breaker III], a timing switch II I, a thermo- 10 interval after the signal has not been restatic switch I31 and a push button switch I26, sponded to. all preferably mounted on a common panel in In accomplishing these and other objects of convenient position relatively to the etching apthe invention, I have provided improved details paratus. As shown in the drawing, the switches of structure, the preferred form of which is illus- I04 and I05 are connected in the branch con- 15 trated in the accompanying drawing, wherein: ductors H6 and H8 leading to the respective The single figure is a wiring diagram of an motors. automatically controlled circuit embodying the As previously mentioned, the positive terminal features of the present invention and showing the of the generator I is connected directly with the circuit in association with an electrical etching conductor 98 leading to the terminal clamps 20 apparatus. which support the plate to be etched, but the Referring more in detail to the drawing: negative terminal thereof connects with the I de i nates a timin an si nallin circuit switch arm H9 of the circuit breaker H0 by e o y the es of the present invention means of a conductor I20. The circuit breaker and which is especially suitable for use in connecswitch arm, when closed, engages a contact I2l tion with an electrical etching apparatus wherein forming a part of an ammeter shunt I22, which a plate 2 to be etched is supported in a tank II, in turn is connected with the bus bars connecting consisting of side, end and bottom Walls I2, I3 the cathodes It by the conductor 22, previously and ely protected on both the inner mentioned. The circuit breaker includes a holdand outer sides from attack of an electrolyte soluing coil I23 that is connected with the positive 30 tion contained therein and in which the plate is side of the generator 'I by a wire I24, also conimmersed. necting with one of the terminals I25 of the Mounted On the bottom of the tan and supvoltmeter I08. The other end of the holding coil ported in spaced relation therewith on suitable connects by a wire I26 with the switch I06 and the insulators I5, is a series of cathodes I5. Each other terminal of the switch is connected by a cathode I6 is constructed of conductive material wire I2'I with the negative side of the circuit and includes a bar of sufiicient length to extend breaker switch arm H9, The wire I27 also consubstantially across the width of the tank and nects with the other terminal of the voltmeter has a flat upper portion I'I exposed to the electroto complete the circuit therethrough.

40 lyte solution to collect current passing from the It's, is thus obvious that when the switch I06 40 plate across the electrolyte, as later described. is closed, current will flow through the wire I24, The respective ends of each cathode are provided holding coil I23, wire I26, switch I06, wire I21, with terminals I8 that extend through the inconductor I20 to the generator I, completing a sulators and connect with bus bars 20 to which is circuit through the holding coil to hold the switch connected a suitable conductor 22 supplying curarm I I9 in closed position. When the switch arm 45 tof the circuit breaker is closed upon energization The plate 2 is oscillatably mounted on a reof the holding coil, current flows through the conciprocatory frame 46 carrying an agitator 40 for ductor 98, plate terminal clamps 68, through the effecting agitation of the electrolyte, the frame plate 2 being etched, through the electrolyte to 5 being actuated by a motor 39 to effect oscillation the cathodes I6, through the conductor 22, am- 50 of the plate and actuation of the agitator. The meter shunt I22, circuit breaker H0 and con plate 2 is connected by terminal clamps 86 to ductor I20, back to the generator. The etching, flexible conductors 91 having connection with a therefore, will continue as long as the switch arm main conductor 98 and which cooperates with the I I9 is closed. The etching of the plate is so rapid conductor 2| to connect a generator 1 for supthat a few seconds over or under exposure of the 55 plate to active electrolyte may result in over or under etching of the plate. I, therefore, provide the time switch for interrupting the etching circuit after an interval determined by practice to give the best etching effects for the character or kind of plate being etched.

The timing mechanism includes a switch arm I28 adapted for connection with the wire I26 through wire I29. The other side of the switch is connected by a wire I30 with one end of a resistance winding I3! that is connected by a wire I32 with the fixed contact I2I of the circuit breaker.

Therefore, when the time switch is closed, current can also flow from the holding circuit through the resistance I3I, the path of the current being as follows; from the positive side of the generator through the wire I24, holding coil I23, wire I26, wire I29, switch arm I28, wire I30, resistance I3I, circuit breaker switch contact I2I, circuit breaker arm H9, and conductor I20 back to the generator. The resistance I35 is, therefore, in series with the holding coil I23 to prevent injury thereto incidental to the heavy current required in the etching process. When the switch arm I28 is opened by the timing mechanism, the circuit through the holding coil I23 and resistance I3I is broken to effect release of the arm I II) of the circuit breaker, thereby breaking the etching circuit to suspend etching action on the plate.

In order to control the output of the generator the negative terminal of the generator winding I33 is connected by a wire I34 with the rheostat I09, through which a circuit is completed to the negative side of the generator by a wire I35 connecting with the switch arm H9. The positive side of the field winding, of course, is connected to the positive side of the generator as in conventional generator design.

Since the etching time is automatically controlled, it is not necessary for the operator to be in constant attendance, and he may be released for other duties While the plate is being etched. The apparatus is, therefore, provided with a signal to audibly advise the operator when the etching current is suspended. This is accomplished by connecting a buzzer or other signal I35 in the generator circuit, as now described.

Connected with the conductor I32 is a wire I32 leading to a thermostatic element I37, including a temperature responsive blade I38 that is movable to and from fixed contact I39 responsive to temperature of the resistance I3I, the contact I39 being connected to a switch I40 by a Wire ItI. The switch I40 is coupled with the switch I55 controlling the agitator motor and is closed or opened simultaneously therewith. The switch I40 is connected with one terminal of the buzzer through a wire I42, and the other terminal of the buzzer is connected by a wire I 43 with the circuit breaker arm II9 completing a closed circuit through the electrolyte solution.

The thermostat contact is closed whenever cur rent is flowing through the holding coil I23, but due to the fact that the buzzer circuit is substantially shorted out when the circuit breaker is closed, the full voltage required to actuate the signal is not impressed on the signal circuit. However, when the circuit to the holding coil is broken to suspend the etching operation, a full current sufiicient to actuate the signal will then flow from the generator through the wire 98, across the electrolyte to the cathodes, through the wire 22, ammeter shunt I22, wire I32, thermostat I38, wire I4I, wire I42, buzzer I36, wire I43, wire I21, and conductor I20 back to the generator.

This current, however, is not sufiicient to produce an etching effect upon the plate because the buzzer is in series with the electrolyte solution. The signal will continue to operate until the switch I05 is opened or until the coil I3I cools sufficiently to effect breaking of the buzzer circuit by means of the thermostat I31.

The ammeter I01 is connected to the shunt by wires I44 and I45, as in customary practice.

In operating an apparatus constructed as described, the clamps 66 are attached to the plate to be etched. The switch I05 is then closed to energize the motor 39 to eITect oscillation of the plate and reciprocation of the agitator.

The switch I04 is then closed to energize the motor II2 to drive the generator, after which the time switch III is set so that the circuit to the holding coil will be broken after a definite time interval. The switch I06 is then closed to eiTect energization of the holding coil I23, which closes the circuit breaker I I0, whereupon current from the generator flows from the plate through the electrolyte solution to the cathode bars, and back to the generator. The time switch will then be set so that the circuit to the holding coil will be broken after a definite time interval.

The amount of the etching current is, of course, controlled by regulating the field rheostat so that the ammeter I01 and the voltmeter I08 indicate that the desired current is flowing through the electrolyte solution. When the time switch breaks the circuit to the holding coil I23, the switch arm I I will be released to break the etching circuit, whereupon current is caused to flow through the alarm circuit to energize the buzzer, thereby advising the operator that the etching process has been completed.

In the operator responds immediately to the alarm, he will open the switch I to shut down the agitator motor, however if he does not re-I spond immediately to the alarm, the coil I3I, which had been in series with the holding coil I23, cools off to cause the thermostat to break the buzzer circuit. The operator will then suspend the operation of the generator actuating motor II2 by opening the switch I04. The etched plate is then removed from its support on the rocker frame, completing the etching operation.

It is thus obvious that the etching process is stopped exactly at the desired point, and that there is no danger of over or under etching the plate.

What I claim and desire to secure by Letters Patent is: I

1. In a circuit for supplying current to a load connected therewith, a current supply connected with said circuit, a switch connected in the circuit between the current supply and the load, a signal, a signal circuit connecting the signal with the current supply circuit for supplying a signal voltage when the switch is opened, a slowly opening switch in the signal circuit, and common means for closing the main switch and the signal switch and for effecting opening of the main switch after a predetermined time interval and permitting delayed opening of the signal switch.

2. In a circuit for supplying current to a load connected therewith, a current supply connected with said circuit, a main switch connected with the circuit between the current supply and said load, a signal, a signal circuit connecting the signal with the current supply circuit for supplying a signal voltage while the main switch is open, a thermostatic switch in the signal circuit, a timing circuit connected Withthe supply circuit, a solenoid in the timing circuit for closing the main switch, a timing switch in the timing circuit for breaking said timing circuit to effect opening of the main switch after a predetermined time interval whereby a signal current is caused to flow in the signal circuit, and a resistance energized while the main switch is closed in the zone of said thermostatic switch for effecting closure of the thermostatic switch when the main switch is closed to establish the signal circuit and to permit delayed opening of the thermostatic switch when the main switch is opened responsive to the timing switch.

3. In a circuit for supplying current to a load connected therewith, a current supply connected with said circuit, a main switch connected with the circuit between the current supply and said load, a signal, a signal circuit for supplying a signal voltage while the main switch is open, a thermostatic switch in the signal circuit, a timing circuit connected with the supply circuit, a solenoid in the timing circuit for closing the main switch, a timing switch in the timing circuit for breaking said timing circuit to eiTect opening of the main switch after a predetermined time interval, a resistance coil energized while the main switch is closed in the zone of said thermostatic switch for effecting closure of the thermostatic switch when the main switch is closed to establish the signal circuit and to permit delayed opening of the thermostatic switch when the main switch is opened responsive to the timing switch, and a switch connected with the timing circuit and the supply circuit to initially energize the solenoid for effecting closure of the main switch.

4. In a circuit of the character described, a circuit breaker in said circuit normally retained in circuit breaking position, a holding coil included in said circuit breaker, a holding circuit connected with the holding coil, means passing a current through the holding circuit to energize the holding coil for closing the circuit breaker, a heating element in the holding circuit energized by current flowing in said circuit, means for interrupting the holding circuit, a signal, a signal circuit energized when the circuit breaker is open, and a thermostatic switch in the signal circuit and located in the heating influence of said heating element to close the signal circuit when a heating current flows through the heating element and permit the signal circuit to be broken when current ceases to flow through the heating element upon opening of the holding circuit.

LOUIS E. HOLLAND. 

